Pulse generator



June 8, 1948. D. E. KENYON PULSE GENERATOR Filed April 20, 1943 'INVENTOR DAVID E. KENYON BY m/fl 9412 ATTORNEY Patented June 8, 1943 UNITED STATES PATENT OFFICE PULSE GENERATOR David E. Kenyon, Smithtown, N. Y., assignor to The Sperry Corporation, a corporation of Delaware Claims. 1

The present application is a countinuation-inpart of my copending application Serial No. 470,693, filed December 30, 1942.

The invention relates to electronic circuits and concerns pulse-forming circuits particularly.

It is an object of my invention to provide improved electronic circuits and methods for controlling electric currents.

It is another object of my invention to provide an arrangement for generating pulses and controlling pulse duration and spacing by the natural constants of a tuned or resonant circuit.

Still another object of my invention is to provide an arrangement for controlling interruption of current in a resonant element.

Still another object is to provide an arrangement for making pulse duration correspond to a half-cycle of oscillation.

Still another object is to provide an arrangement for sustaining natural oscillations.

A further object of the invention is to provide an arrangement for forming marking pulses and controlling them in time duration and frequency.

Other and further objects and advantages will become apparent as the description proceeds.

In carrying out my invention in its preferred form, I provide resonant elements and electric discharge devices or valves for controlling the currents therein. I arrange the circuits so that currents flowing in the resonant elements are interrupted abruptly by the discharge devices to initiate trains of oscillations which may be cutoff after the first half-cycle in order to form pulses having a pulse duration equal to a halfcycle of an oscillation in the resonant circuit or element. Trigger circuits are employed for controlling the frequency of initiation of the pulseforming oscillations.

A better understanding of my invention will be afforded by the following detailed description considered in connection with the accompanying 1 drawing, and those features of the invention which are believed to be novel and patentable will be pointed out in the claims appended hereto.

The single figure of the drawing is a circuit diagram of one embodiment of my invention.

In the form of apparatus illustrated in the drawing, there is a repeating trigger circuit II which may take the form of a multivibrator type of circuit comprising two stages represented by electric discharge devices or valves [2 and I3. The devices l2 and [3 may take the form of vacuum tubes and are shown for the sake of illustration as pentode tubes. As shown, the tubes I2 and I3 comprise anodes l4 and I5, grounded cathodes l6 and I1, control electrodes or grids I8 and I9, suppressor grids 2| and 22, and screen grids 23 and 24, respectively. The anodes and control grids are conventionally cross coupled by means of coupling condensers 25 and 26 and grid leak resistors 21 and 28. The control grids I8 2 and I9 may be positively biased, and for roviding adjustment of the repetition rate of the multivibrator circuit H, an adjustable bias-providing potentiometer 29 may be provided. The potentiometer 29 comprises a resistor 3| connected across a source of anode supply current 32 and an adjustable tap 33, to which the control grids l8 and 19 are connected through the resistors 21 and 28, respectively.

The anode of one of the tubes, for example the anode I5, is connected to the positive terminal of the power supply 32 in a conventional manner through aload resistor 34. The anode of the other multivibrator tube, in this case the anode I4, however, is connected to the positive terminal of the supply source 32 through an anode resistor which is split into two parts 35 and 36. For providing the desired delay between the direct and delayed pulses to be triggered by the multivibrator circuit II, a delay line 31 is interposed between the anode resistor parts 35 and 33 in series therewith.

For inducing oscillations, a pair of resonant elements 38 and 39 may be provided. The elements 38 and 39 may take the form of anode impedances or chokes, the distributed capacity of which combined with the inductance serve to form inductance-capacity resonant circuits.

For controlling current in the chokes 38 and 33, a pair of electric discharge devices or valves 4| and 42 ma be provided. The devices 4] and 42 are shown as taking the form of triode-connected pentode vacuum tubes. The chokes 38 and 39 are included in the anode circuits of the tubes 4| and 42, and preferably decoupling resistors 43 and 44 are also connected in series with the chokes 38 and 39 to the positive bus 45 connected to the positive terminal of the power supply 32.

The tube 4| includes a control electrode or grid 45 which is resistance-capacity coupled to a junction terminal 47 between the delay line 31 and the anode resistor 36 of the tube l2. Likewise, the tube 42 includes a control electrode or grid 43 which is also resistance-capacity coupled to the anode circuit of the tube l2. In this case, however, the coupling is to the other end of the delay line 31, namely, to a junction terminal 49 between the delay line 3'! and the anode resistor 35 of the tube I 2.

For extinguishing oscillation in the chokes 38 and 39 upon reversal of polarity, unilateral current-conducting devices or rectifiers 5] and 52 are connected across the chokes '38 and 39, respectively. The rectifiers 5! and 52 may, if desired, take the form of diode vacuum tube elements enclosed in a single envelope 53 to form a twin diode tube.

In order to isolate the tubes 4| and 42 from possible reaction from output circuits, stages 54 and 55 may be provided, which serve as buffers ment 82.

betweenthe tubes it and 42 and pulse output Marker pulses, may Joe-taken from a suitable point I in the circuit of "the amplifier 31., Pref- I I erably, however,a clipper andbuffer stage 81' is I I interposed betweenthe amplifier ,6! and a clipper I output terminal 83.

The stage 8'! may take the ;-form of apentode vacuum: tube connected, as

,a cathode follower having a controlelectrode- 89 =resistance-capacity coupled to the anode 14 51, the buffers 54' and '55 maybe connected as,

cathode follower stages. I

I For providing marker pulses which arexsym chronous with the'direct'and'delayed pulses produced at the terminals 5'6 and 5?, another reschant circuit 6! and an associated wcurrentcontrolling tube'EE m'aybe provided; The tube 62 may also take theform of ,avtriodeaconne cted i pentode by way of example and is connected v to the commonpowersupplysource 32 by means I of the positive bus 45.

in this case,'however, isicon'nectedin the cathode circuit of the tube '62 instead of theganode circuit;

' I For causing the tube 62 toiinterrupt current in the resonant circuit 6l,with;the same frequency as the occurrenceof the .pulses at the terminals I 56 and 51,- a resistance-capacity.coupling 3 is I provided between a suitable point in ,the,;mul,ti--

' vibrator circuit 51 5 for example the terminal 43,

and a control electrode 154 :in the tube 2;

' The'resonanticircuit .61; as shown, may com- I prise aninductance B5 in :parallelywith;a separate,

' For sustaining oscillations-in the I I I I condenser 66. resonant circuit 6% and avoiding any loading thereof; a negative resistance element or un-: tuned'amplifier 61 may be provided; I I v The amplifier 67, as shown by Wayof rilluse tration, takestheform' ofapair of triode vacuum I tube elements .63 and '69 which may be'mounted I in a cominonenvelope to form atwintrioda-although my invention is not limitedto the useof triode elements. In thearrangement illustrated, the triode element 6 3 comprisesan anode H, a cathode Y2, and a control electrode orgrid 13, and the triode 69 comprises corresponding elements, [5 and 16.

The anodes"?! and M are connected through anode impedances or resistors 11 and 'lB to the positivebus Q5 of the power supply '32,'preferably through a resistance-capacity decoupling circuit 19. The grids and anodes of the twin triode amplifier 61 are cross coupled by resistance-capacity elements, comprising a coupling condenserill between the anode H and. the control grid 16 with an associated grid leak resistance 82 and a coupling condenser 83 between the anode l4 and the control grid 13 without any grid leak resistor correspondingto the ele- The control grid '53 isgrounded, instead; through the inductance 6.5. For bias and stabilization, cathode resistors 85 and 86 may be provided.

It will be observed that the amplifierb"! is The resonant. circuit 06 i I I "of the twin triode amplifier, 67 and having a I cathode terminal iil connected to the clipper out-,

'putterminal 88. The circuit constants may be so chosen that the output o t e a p e 57 overdrives the amplifier .87 and thereby causes I clipping of negative half-cycles.

The timing or determination ur ne repetition,

rate of-the generated pulses is controlled by the I multivibrator-trigge1ing circuit15.1 {The tubes l2- 7 '3 become-alternately conducting at alrate 7 determined Icy-the circuit-constantsandthe Set,

tingof the pulse frequency potentiometer 29. I

I Wheneverthe conduction-is shifted from the tube I v 1,3 to the tube i2 renderingthe-tube l2 conduct- I I ing,: the sudden flowvof current-through the anode I resistor Ski-produces asharp potential dropatthe terminal A l which is transmitted through the, I i

and i condenser ccupling to the control grid A6 of the tube 5, which, normally conducts current. The Y I I negativeimpul-se applied'to thegrid .dfi howewer,v -drives'thetube 5 beyond cut-off and abruptly interrupts the flow of current in the choke-38.

An inductive voltagethereupon'appears in choke tt and transfers a positive potential-to the .con-

connected in a manner analogous to a multivibrator circuit or resistance-capacity ,coupled two-stage feed-back oscillator. The arrangement transmitted-to the tube pulse-at terminal-51the negative-impulse islalso ,trol grid 58 I o f the buffer 1 54% :During the first v I halbcycle-ofthe train of oscillations which tends to beinduced in the choketfi, the grid 58 remains at positive potential, andra positive. half-cycle appears at the direct pulse terminates. I The l I I I :oscillationin the choke 38 iseXtinguishedin-the I l n xt'half cycie l'however -by therectifierfilwhich I 7 short circuitsthechoke 35 for voltageoi reversed polarity whichtends tobe induced during the second half-cycle.

A similaraction takes place in the elements comprising-the choke 39, the current-extinguishing tube :i2 ,-andthe buffer 55. However, thecontrol grid- 38 of the tube-Z- iscoupled to the other end-}? of the delay lined? so that-a-negative .impulse correspondingto that from the terminal ells-not appliedto the control grid d3 until the negative impulse at the terminate?- is propagated along the delay line-3? to the-otherpendAS. It will be understood that a delay line is a-circuit element resembling a transmission line having suchelectricallengthzthat the desired-time delay is involved in thetransmission of the pulsefrom oneend*of-lthe'lineto the: other. The resistance ofthe-resistor tE- ismade equal-to thelcha-racteristic impedanceotthe-line 31. 'Ihe. delayline 3i -may, of course, 'bea compact unit comprising relatively large inductances and condensersin the form ofan artificial transmission line.

Atthe same-time that a negative impulse is 52 to form the vdelayed transmitted-to=thecontro1 grid-M. of thetube '62 todrive the: tube 152 beyond-cut-offi and extinguish the current which is normally flowing through the inductance- 65 of the resonant element .fil.

Theinterruption of current in-theinductance-65 a voltage-therein-lwhich drives the control grid-73 of thexamplifiertl negative. Since the outputpfthearnplifier: 6l.is fed backto the resonant circuit-til throughathe coupling condenser 83, it; acts: as a negative resistance andtends ,to

sustain; the oscillations in thelresonantcircuitfil vib-rator H, when current shifts back from the tube 22 to the tube 13, the potential of the grid or the tube 92 rises, causing the tube to become a hort circuit for the resonant circuit 9 i, and the oscillations therein are extinguished. Thus, for each cycle of the multivibrator H, the complete circuit produces a direct pulse at the terminal 56, and a delayed pulse at the terminal followed by a train of marker pulses at the terminal 38. The pulse from the terminal 5 may be used for tripping the sweep-wave of a cathode ray oscilloscope 93 or a synchroscope having sweep and signal terminals 94 and 65. The pulse from the terminal 57 may be used for tripping phenomena to be observed in a cathode ray oscilloscope screen 96, such phenomena being produced for example by a generator 97, and the sweep wave by a generator 98, and the marker pulses from the terminal 98 may also be thrown upon the cathode ray oscilloscope screen 96 to serve as a time scale.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A delayed pulse generator comprising triping circuit means, regenerative feed-back means for producing sustained oscillation of the tripping means, a delay line included therein, a pair of resonant elements, current interrupting means associated with said resonant elements, couplings between the ends of said delay line and. said interrupting means, oscillation extinguishing means connected to said resonant elements, and means for forming pulses corresponding to initial halfcycles of oscillation in said resonant elements.

2. A delayed pulse generator comprising a pair of pulse forming circuits of the interrupted-current choketype, means tripping said pulse forming circuits, and delay means interposed between said tripping means and one of said pulse forming circuits.

3. A marker pulse generator comprising a trigger circuit, a resonant circuit, a current interrupter for said resonant circuit triggered by said trigger circuit, an untuned, regenerated feedback, stabilized amplifier so coupled to said resonant circuit as to supply energy thereto, and a bufier stage driven by said amplifier.

4. A marker pulse generator comprising, in combination, a resonant circuit having constants determining pulse width, current interrupting means for said resonant circuit to induce oscillations therein, and a resistance-capacity coupled two-stage feed-back amplifier so coupled to said resonant circuit as to supply energy thereto, whereby a stabilized marker pulse appears as the output of said amplifier.

5. In combination, an oscillator of the electric discharge device type having an inductance-capacity resonant circuit for determining the frequency thereof, and a trigger circuit connected for abruptly varying direct-current fiow through the resonant circuit, and an amplifier acting as a negative resistance connected to initiate oscillation of said circuit immediately at an amplitude substantially as great as the sustained oscillation amplitude.

6. In combination, a resonant circuit having a predetermined natural period of oscillation, means for shock-exciting said resonant circuit, and a negative-resistance unit coupled to said resonant circuit for sustaining oscillation.

7. In combination, an intermittently triggered tuned oscillatory circuit, a resistance-capacity coupled amplifier stage coupled to said resonant circuit, and a second amplifier stage coupled to said first stage and having a feed-back connection to said first stage, said couplings being so arranged that energy is supplied to said resonant circuit by said amplifier stages,

8. In combination, an electric discharge device having a cathode lead with a tuned circuit therein whereby oscillation may be induced in said tuned circuit by interrupting discharge in the device, an amplifier with a control grid and a non-inductive regenerative feed-back coupling to the grid, and means connecting said tuned circuit to said grid for sustaining oscillation in said tuned circuit.

9. In combination, an electric discharge device having a cathode lead with a tuned circuit therein whereby oscillation may be induced in said tuned circuit by interrupting dischargein said device, an amplifier with a control grid and a regenerative feed-back coupling to the grid, and a connection between said grid and said tuned circuit for sustaining oscillation in said tuned circuit, whereby resumption of discharge rapidly damps out said oscillation.

10. In combination, a cathode ray oscilloscope having sweep wave and signal wave input terminals, means coupled to the signal wave input terminals for generating a phenomena to be observed in the oscilloscope; a sweep wave generator coupled to the sweep wav input terminals, means for tripping the sweep wave generator, means for later tripping the phenomena-generating means, and means for supplying marker pulses to said signal wave input terminals, said marked pulses being initiated simultaneously with the tripping of said phenomena-generating means.

DAVID E. KENYON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENIS Number Name Date 1,910,151 Dolmage May 23, 1933 1,963,751 Llewellyn June 19, 1934 2,063,025 Blumlein Dec. 8, 1936 2,085,402 Vance June 29, 1937 2,103,090 Plebanski Dec. 21, 1937 2,121,359 Luck et al June 21, 1938 2,139,432 Andrieu Dec. 6, 1938 2,153,202 Nichols Apr. 4, 1939 2,181,309 Andrieu Nov. 28, 1939 2,266,401 Reeves Dec. 16, 1941 2,266,668 Tubbs Dec. 16, 1941 2,277,000 Bingley Mar. 17, 1942 2,284,219 Loughren May 26, 1942 2,297,926 Usselman Oct. 6, 1942 2,300,999 Williams Nov. 3, 1942 2,313,967 Read, Jr. Mar. 16, 1943 2,363,810 Schrader et a1 Nov. 28, 1944 2,373,145 Sensiper et a1 Apr. 10, 1945 FOREIGN PATENTS Number Country Date 355,705 Great Britain Aug. 24, 1931 516,358 GreatBrltain Jan. 1, 1939 

